The company has been fighting the subpoena, saying that doing so would violate the law in "Country A." In December, a federal appeals court in Washington, DC, struck down the company's argument and ordered it to comply with the subpoena. It also imposed a fine for each day the company did not cooperate with Mueller.

The company appealed to the Supreme Court, and Chief Justice John Roberts placed a temporary freeze on the fines while the court considered the case. But the Supreme Court ultimately declined to intervene, holding up the lower court's ruling.

The information, which was supposed to be redacted in the filing, revealed that Mueller believes Manafort lied about sharing confidential Trump campaign polling data with the former Russian intelligence operative Konstantin Kilimnik.

Prosecutors say the information was intended for two Ukrainian oligarchs, and the news prompted speculation over whether Manafort provided the information as part of a quid pro quo for his political consulting work.

His spokesperson denied that was the case, and Manafort's team continues pushing back against Mueller's claim that he breached his plea deal.

Thursday marks two years since BuzzFeed News published the so-called Steele dossier. Many of the dossier's claims remain uncorroborated. But several allegations have proven, in part, to have held up over time.

That includes some of the document's claims about a direct link between Russia and the 2016 hack of the Democratic National Committee and subsequent dissemination of stolen emails through WikiLeaks; some of Trump's business dealings in Russia; former Trump campaign adviser Carter Page's meetings during a shadowy Moscow trip; and Manafort's deep ties to Russian and Ukrainian interests.

Federal prosecutors in New York indicted Natalia Veselnitskaya, the self-identified Kremlin "informant" and lawyer, accusing her of secretly working with a top Russian prosecutor to hamper a Justice Department investigation into an alleged money-laundering operation that involved an elaborate Russian tax-fraud scheme and implicated high-level Kremlin officials.

Veselnitskaya made headlines in 2017 when it surfaced that she met with several top Trump campaign officials during the 2016 election to offer them compromising information on then Democratic candidate Hillary Clinton "as part of Russia and its government's support" for President Donald Trump's candidacy.

Deputy attorney general Rod Rosenstein is said to be preparing to leave the Justice Department after William Barr, Trump's nominee for attorney general, is confirmed by the Senate later this month.

Some media reports said Rosenstein would stay on not only until Barr's confirmation, but also until Mueller's investigation was nearly wrapped up.

Legal experts said the news itself indicates the investigation could formally end soon, but that it is an unlikely possibility given a number of looming indictments that have yet to drop. A federal judge in Washington, DC, recently extended Mueller's grand jury for another six months.

Either way, one Justice Department veteran said the myriad court cases stemming from the probe would continue past Rosenstein's departure, potentially generating new evidence, cooperators, and charges.